Fix to the way extents are calculated in SYSTABLEPART

(Originally posted 2006-01-12.)

Running out of extents for DB2 tablespaces can be a real bore. So installations like to monitor them (and I like to see them too). APAR PK12653 describes a fix to the recording of the number of extents in the SYSTABLEPART Catalog table. This fix is only available for DB2 Version 8.

RUNSTATS updates this table using the extents count in the PB0 control block. This is updated on physical data set OPEN, but not when the data set gets extended. So it can be inaccurate.

The changes are two-fold:

  • Refresh the PB0 value at the end of extend processing.
  • Notify other data sharing members at the end of extend processing.

This should make the number a lot more accurate in SYSTABLEPART because RUNSTATS will be sampling a more accurately maintained control block field.

Published by Martin Packer

I'm a mainframe performance guy and have been for the past 35 years. But I play with lots of other technologies as well.

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